In recent years, microelectromechanical Systems (MEMS) plays a great role in the development of optical systems. MEMS provides a semiconductor-like lithographic batch fabrication process which makes it easy to make micromechanical and microoptical elements integrated with control electronics on a single chip. By combining with the microoptics or waveguides, it grants the flexibility of light path design to be free-space or guided-wave. This advanced technology has been leveraged to create many crucial components for telecommunication application, such as optical switches, variable optical attenuators, tunable filters. The invention is one of the optical switches utilizing MEMS technology.
U.S. Pat. No. 6,292,600 discloses a free-rotating hinged micro-mirror switching element operated in “open” and “close” states. The micro-mirror comprises a mirror connected to the substrate by free-rotating micro-hinges. The hinges include one or more hinge pins and one or more hinge staples. Pushrods are connected at one end to the mirror and at the opposite end to the translation stage with hinge joints. And the actuated component is the scratch-drive actuator (SDA). Through applying appropriate voltage to the SDA, the SDA can be deformed or moved to a certain extent. The deformation or movement in turn causes the pushrods to act upon the mirror and rotate it to a predetermined position or angle from the substrate. Such design is able to turn the linear movement of the pushrods into rotation of the mirror and relatively reduce the entire device dimensions. However, because the degree of freedom of the mirror rotation is extremely sensitive to the optical fiber coupling efficiency, the mirror rotation angle has to be precisely controlled and encounters much difficulty.
Besides, in U.S. Pat. Nos. 6,526,198 and 6,556,741, the micro-mirror switch includes a substrate, an electrode coupled to the substrate, and a micromachined plate rotatably coupled to the substrate about a pivot axis. The micro-mirror has an orientated reflective surface mounted to the micromachined plate. An electrical source is coupled to the electrode and the micromachined plate. When voltage is applied, the electrostatic force causes the actuator move downward. The high reflection mirror surface is assembled to the actuator and perpendicular to the substrate. In order to avoid causing electrical short when the mirror moves down, a landing electrode with a buckle beam is specially used. Though the structure may provide precise movement, but each optical switch element needs additional assembly, which consumes time and a lot of work.